1. Field of the Invention
This invention pertains to fiber optic connectors generally, and specifically to an improved optical sub-assembly and nose block used therein. The detachable connectors of the present invention deliver excellent performance, and are manufacturable using few piece parts and low cost processes and techniques.
2. Description of the Related Art
Fiber optics offer much hope for the future of communications and computing. Optical energy may be modulated at much higher frequencies than electrical energy. In addition, and unlike electrical energy, optical energy can be constrained within small fibers. Optical fibers allow multiple secure high bandwidth transmissions to occur within close physical proximity of each other. The long distance telecommunications and military industries have gained much benefit from fiber optics.
However, the cost of fiber optics has been so great as to present an obstacle to wide spread applications such as desktop computing or local area networks. Fiber optics have only been applied where benefits were great enough to offset the formidable cost. Much research has been devoted to ways of achieving the benefits of fiber optics without the high cost, both by the present assignee and others in the field.
There are several factors which tend to keep the cost of fiber optics high. Among these are the need for precision alignment and exclusion of foreign matter, both which would otherwise lead to undesirable losses of optical signal. When the center to center axial alignment of two 100 micrometer fibers is mismatched by only 10 micrometers, there is a resultant 0.6 db loss in optical signal strength. The manufacturing processes involved in alignment to that precision are challenging. Since foreign matter can also block optical transmission across any junctions which are not sealed, manufacturing processes must not only cater to precise alignment, but must also address cleanliness of the interconnection and appropriate sealing.
To compound the issue even further, optical fiber is made from high-purity glass materials, and although somewhat flexible, the fiber is still brittle and may be easily damaged. Component design and manufacturing processes therefore must also cater to the fragile fiber.
Opto-electronic components are inefficient at converting electrical energy to optical energy, and, as a result, these components often dissipate large amounts of thermal energy. Cooling the higher power components to ensure they do not overheat, and to extend component operating life, is very important. Cooling also comes at a cost, requiring some form of heat sinking and more expensive mounting. Other factors which contribute to the cost of fiber optics are beyond the scope of this disclosure and so will not be considered herein.
Prior art fiber optic connectors are illustrated in U.S. Pat. Nos. 5,434,941, 5,450,515, and 5,452,390, incorporated herein by reference. In those prior art designs, great care was taken to ensure the hermeticity of the connector package to prevent influx of contaminants or corrosive agents which might affect long term reliability. Unfortunately, the requirements for hermeticity can not be achieved in the present day art without significant expense.
In addition, the prior art designs used an optical sub-assembly which only supported the opto-electronic device. All other electronics were mounted upon a multi-layer glass and ceramic substrate commonly referred to as Low Temperature Co-fired Ceramic, or LTCC. The high power driver that directly connects to the opto-electronic device, in transmitter applications, was mounted on the LTCC substrate. In order to cool the driver, special thermal vias and heat spreaders were required. The physical separation between the driver or receiver electronics mounted on the LTCC and opto-electronic components mounted on the optical sub-assembly also resulted in the potential for undesirable circuitry cross-talk and ringing.